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network delays
Complete

Summary

Units

  • b for bits, B for bytes
PrefixSize
Kilo10³
Mega10⁶
Giga10⁹
Tera10¹²
Peta10¹⁵
Exa10¹⁸
Zetta10²¹
Yotta10²⁴

Concept

Packet loss

  • packet is dropped if the router’s buffer is full
  • previous node/source may retransmit if no reply is received

Packet delay

  1. processing delay

    • check errors and determine output link

  2. queueing delay

    • time spent waiting in the queue

  3. transmission delay

    • for packets of -bits
    • at transmission rate
  1. propagation delay
    • for physical link of length
    • at the propagation speed of the medium

propagation speed of light in a fiber optic cable is ~2×10⁸ m/sec

ClientSwitchServerp1p1r1r1dpropdtransdproc+dqueueServerActionEnd-to-EndDelayRoundTripTime

Utilization

  • how much time is spend on work vs waiting

Application

Data transmission

  • single packet
ClientSwitchServerp1p1dpropdtransEnd-to-EndDelay
  • message segmentation
    • less delay with pipelining
    • more overhead, header for each packet
ClientSwitchServerp1p1p2p2p3p3p4p4p5p5dpropdtransEnd-to-EndDelay

Extra

Tikz template for 1 hop network delay diagrams

latex
\usepackage{tikz}
\usetikzlibrary{arrows.meta,positioning,calc,decorations.pathreplacing}
\begin{document}
\def\dprop{0.8}
\def\dtrans{1}

% Host timeline (vertical line representing a host)
% #1 = x position
% #2 = name
% #3 = label text
\newcommand{\host}[3]{
  \draw[thick] (#1,0) -- (#1,-6) node[pos=0,above] {\textbf{#3}};
  \coordinate (#2) at (#1,0);
}

% Diagonal arrow going down-right
% #1 = source
% #2 = destination 
% #3 = label
% #4 = vertical offset from start

\newcommand{\trans}[4]{ 
	\coordinate (pstart) at ([yshift=#4]#1);
	\coordinate (pend) at ([yshift=#4-\dprop cm]#2);
	\coordinate (pstart-bottom) at ([yshift=#4-\dtrans cm]#1);
	\coordinate (pend-bottom) at ([yshift=#4-\dprop cm-\dtrans cm]#2); 
	% Draw filled parallelogram
	\fill[opacity=0.3] (pstart) -- (pend) -- (pend-bottom) -- (pstart-bottom) -- cycle;
	% Draw outline
	\draw[thick] (pstart) -- (pend) -- (pend-bottom) -- (pstart-bottom) -- cycle;
	% Draw arrow at leading edge
	%\draw[-{Stealth[length=3mm]}, very thick] (pstart) -- (pend); 
	% Label
	\node[font=\small] at ($(pstart)!0.5!(pend-bottom)$) {#3}; }

% Time marker (horizontal dashed line with label)
% #1 = y position
% #2 = label text
% #3 = x start position
% #4 = x end position
\newcommand{\timemarker}[4]{
  \draw[dotted] (#3,#1) -- (#4,#1);
  \node[left,font=\small] at (#3,#1) {#2};
}

\begin{tikzpicture}

% Define hosts
\host{0}{client}{Sender}
\host{5}{server}{Receiver}

% Transmissions
\trans{client}{server}{$p_1$}{-1cm}
\trans{server}{client}{$r_1$}{-3.2cm}

% Time markers
\timemarker{-1cm}{}{0}{5}

\draw [decorate,decoration={brace,mirror,amplitude=4pt}]
      (0,-1) -- (0,-2) node [midway,left,xshift=-.1cm,font=\small] {$d_{trans}$};
\draw [decorate,decoration={brace,mirror,amplitude=4pt}]
      (0,-2) -- (0,-4) node [midway,left,xshift=-.1cm,font=\small] {RTT};

\end{tikzpicture}
\end{document}

Tikz template for 2 hop network delay diagrams

latex
\usepackage{tikz}
\usetikzlibrary{arrows.meta,positioning,calc,decorations.pathreplacing}
\begin{document}
\def\dprop{0.8}
\def\dtrans{1}

% Host timeline (vertical line representing a host)
% #1 = x position
% #2 = name
% #3 = label text
\newcommand{\host}[3]{
  \draw[thick] (#1,0) -- (#1,-11) node[pos=0,above] {\textbf{#3}};
  \coordinate (#2) at (#1,0);
}

% Diagonal arrow going down-right
% #1 = source
% #2 = destination 
% #3 = label
% #4 = vertical offset from start


\newcommand{\trans}[4]{ 
	\coordinate (pstart) at ([yshift=#4]#1);
	\coordinate (pend) at ([yshift=#4-\dprop cm]#2);
	\coordinate (pstart-bottom) at ([yshift=#4-\dtrans cm]#1);
	\coordinate (pend-bottom) at ([yshift=#4-\dprop cm-\dtrans cm]#2); 
	% Draw filled parallelogram
	\fill[opacity=0.3] (pstart) -- (pend) -- (pend-bottom) -- (pstart-bottom) -- cycle;
	% Draw outline
	\draw[thick] (pstart) -- (pend) -- (pend-bottom) -- (pstart-bottom) -- cycle;
	% Draw arrow at leading edge
	%\draw[-{Stealth[length=3mm]}, very thick] (pstart) -- (pend); 
	% Label
	\node[font=\small] at ($(pstart)!0.5!(pend-bottom)$) {#3}; }

% Time marker (horizontal dashed line with label)
% #1 = y position
% #2 = label text
% #3 = x start position
% #4 = x end position
\newcommand{\timemarker}[4]{
  \draw[dotted] (#3,#1) -- (#4,#1);
  \node[left,font=\small] at (#3,#1) {#2};
}

\begin{tikzpicture}

% Define hosts
\host{0}{client}{Client}
\host{5}{switch}{Switch}
\host{10}{server}{Server}

% Transmissions
\trans{client}{switch}{$p_1$}{-1cm}
\trans{switch}{server}{$p_1$}{-3.2cm}
\trans{server}{switch}{$r_1$}{-6cm}
\trans{switch}{client}{$r_1$}{-8.2cm}

% Time markers
\timemarker{-1cm}{}{0}{5}

\draw [decorate,decoration={brace,amplitude=4pt}]
      (5,-1) -- (5,-1.8) node [midway,right,xshift=.1cm,font=\small] {$d_{\text{prop}}$};
\draw [decorate,decoration={brace,amplitude=4pt}]
      (5,-1.8) -- (5,-2.8) node [midway,right,xshift=.1cm,font=\small] {$d_{trans}$};
\draw [decorate,decoration={brace,amplitude=4pt}]
      (5,-2.8) -- (5,-3.2) node [midway,right,xshift=.1cm,font=\small] {$d_{proc}+d_{queue}$};
\draw [decorate,decoration={brace,amplitude=4pt}]
      (10,-5) -- (10,-6) node [midway,right,xshift=.1cm,font=\small] {Server Action};

\node[font=\small,text=gray] at (2.5,-5.5) {End-To-End Delay};
\timemarker{-5cm}{}{0}{10}
\node[font=\small,text=gray] at (2.5,-10.5) {Round Trip Time};
\timemarker{-10cm}{}{0}{10}

\end{tikzpicture}
\end{document}